Disasters and Disruptions Virtual Oral Abstracts
Dec 01, 2020 02:00 PM - Dec 31, 2020 03:30 PM(America/Chicago)
20201201T1400 20201201T1530 America/Chicago Disasters and Disruptions - Diversions, dredging, subsidence, & erosion (Oral)

The Gulf Coast has experienced - and is experiencing - a variety of disasters and disruptions from the Deepwater Horizon oil disaster (this year being the 10th anniversary), major hurricanes, freshwater inflow events, such as the opening of the Bonnet Carré Spillway and the ongoing COVID-19 health pandemic. For some of these disasters and disruptions, we have a better understanding of human and ecological recovery, with restoration efforts underway or planned to advance recovery. For others, our knowledge of the impacts and the recovery process is more limited. Topics in this track may include new research, perspectives and/or updates on human and ecological impacts, restoration, extension and education and outreach-related discoveries related to these and other major disruptions and disasters affecting the Gulf Coast.

Virtual 2020 Bays and Bayous Symposium melissa.schneider@usm.edu
National Oceanic and Atmospheric Administration logoMobile Bay National Estuary Program logoMississippi-Alabama Sea Grant Consortium logoThe University of Southern Mississippi  logoDauphin Island Sea Lab Foundation logoAlabama State Port Authority logoMississippi Commercial Fisheries United logoGulf of Mexico Alliance logoHydro, LLC logoGeosyntec  logoNorthern Gulf Institute logoGoodwyn Mills & Cawood, Inc. logoNeel-Schaffer, inc. logoHeadwaters LLC logoStantec Consulting Services Inc. logoDog River Clearwater Revival logoEnvironmental Science Associates (ESA) logoThompson Engineering logo

The Gulf Coast has experienced - and is experiencing - a variety of disasters and disruptions from the Deepwater Horizon oil disaster (this year being the 10th anniversary), major hurricanes, freshwater inflow events, such as the opening of the Bonnet Carré Spillway and the ongoing COVID-19 health pandemic. For some of these disasters and disruptions, we have a better understanding of human and ecological recovery, with restoration efforts underway or planned to advance recovery. For others, our knowledge of the impacts and the recovery process is more limited. Topics in this track may include new research, perspectives and/or updates on human and ecological impacts, restoration, extension and education and outreach-related discoveries related to these and other major disruptions and disasters affecting the Gulf Coast.

The effects of inundation on Sagittaria lancifolia using a marsh organView Abstract Watch Recording
Oral Presentation 02:00 PM - 02:15 PM (America/Chicago) 2020/12/01 20:00:00 UTC - 2020/12/31 20:15:00 UTC
Manmade freshwater diversion efforts in Louisiana will likely drive gradual community shifts of brackish and salt-tolerant plants species to more freshwater oriented species. Sagittaria lancifolia, a freshwater dominant wetland species, may replace salt-tolerant species as salinity regimes are altered due to freshwater diversion input. Therefore, the understanding of this species’ inundation-productivity relationship is important to better quantify the effects of diversions on prominent freshwater wetland species. We are utilizing a marsh organ in-situ mesocosm design to study morphometrics and biomass allocation of Sagittaria lancifolia in the Pascagoula River drainage, a freshwater, tidally influenced coastal wetland. Estimated percent inundation times of the six marsh organ levels are 100%, 80%, 60%, 40%, 20%, and 10% respectively. We have noted a positive correlation of this species to increased inundation, and negligible effects of nitrate addition. Continuation of this study includes biomass collection and analysis, and soil chemistry analysis.
Presenters Evan Grimes
The University Of Southern Missisippi
Co-authors
WW
Wei Wu
University Of Southern Mississippi, Division Of Coastal Sciences
GS
Glenn Suir
U.S. Army Corps Of Engineers
Assessment of wave regimes for optimal implementation of marsh terracing in the northern Gulf of Mexico, a modeling approachView Abstract Watch Recording
Oral Presentation 02:15 PM - 02:30 PM (America/Chicago) 2020/12/01 20:15:00 UTC - 2020/12/31 20:30:00 UTC
Marsh terracing is a coastal restoration technique that can dissipate wind driven waves, reduce fetch, and potentially reduce erosion from adjacent marsh platform in the northern Gulf of Mexico. This technique consists of constructing segmented berms of bare soil from sediment excavated within shallow coastal ponds. Over 980 linear km of marsh terraces have been built in Texas and Louisiana in the last 30 years; however very little research has focused on optimization of terrace design and implementation. The objective of this study was to understand wave regimes in marsh terrace fields under a range of wind conditions to identify an optimal terrace design for reducing wave energy. The Simulating WAves Nearshore (SWAN) model was used in this study to compute wind waves at two terrace fields in coastal Louisiana. Simulations were based on real terrace field conditions with and without terraces. Model validation was performed under stationary conditions (constant wind parameters) using wind data from NOAA stations and wave parameters collected by wave instruments during 5 months at each study field. Results from this study will help us to understand wave dynamics in marsh terrace environments with different terrace designs and without terraces. At the end of this project we expect to identify the most effective terrace design for reducing wave energy, which is related to marsh erosion, leading to an optimal implementation of this restoration technique in the northern Gulf of Mexico.
Presenters Raul Osorio
Mississippi State University
Co-authors
AL
Anna Linhoss
Mississippi State University
AS
A. Skarke
Mississippi State University
MB
Michael Brasher
Ducks Unlimited Inc
JF
Joseph French
Mississippi State University
Subsidence Rates and Elastic Motion of The Mississippi Gulf CoastView Abstract Watch Recording
Oral Presentation 02:30 PM - 02:45 PM (America/Chicago) 2020/12/01 20:30:00 UTC - 2020/12/31 20:45:00 UTC
As glacio-eustatic sea-level change continues to impact coastal communities, an increased understanding of surface elevation changes within coastal areas is crucial to predicting the fate of coastal infrastructure, ecosystems, and habitats. The purpose of this study is to examine the spatial extent and variability of subsidence using an east-west transect of Continually Operating Reference Station (CORS) receivers across the Mississippi Coast. The main objective of this study was to use mean differences in antenna height to determine subsidence rates along the Coast of Mississippi between 2006-2018. Research questions included: What are the mean rates of vertical displacement for points along the transect; 2) What are the differences in mean rates of displacement and 3) What is the change (Δ) in mean antenna heights between final (tf) and initial (ti) times of observation for each receiver over the span of observations? The hypotheses of the study were: 1) Yearly mean rates of vertical displacement are 2.5 mmy-1 (±0.5mm) and 2) subsidence along the Mississippi Gulf Coast has occurred at a constant rate and is uniformly spatially distributed. The temporal resolution of MSIN & MSEV spatial data spanned from 2012-2018 whereas ALDI spanned 2010-2018. MSGB Spanned 2011-2018 and MSWV spanned 2010-2016. The longest series was MSGA spanning 12 year from 2006-2017 and the Shortest was MSHI spanning 2018-2020. Overall mean rates of subsidence for MSIN and MSEV between 2012-2018 were ~ 1.81 mmy-1 and 1.25 mmy-1 respectively. MSWV’s rate was much lower than MSIN and MSEV at ~ 0.48 mmy-1. Mean rates of vertical displacement for ALDI between 2010-2018 was 2.61 mmy-1 whereas between 2011-2017 for MSGB rates were ~ 1.00 mmy-1 and MSHI fell in at ~ 1.54 mmy-1.
Presenters Bill Funderburk
USM Gulf Coast Geospatial Center
A Retrospective Analysis of a Dredging and Disposal Problem AreaView Abstract Watch Recording
Oral Presentation 02:45 PM - 03:00 PM (America/Chicago) 2020/12/01 20:45:00 UTC - 2020/12/31 21:00:00 UTC
Few studies have examined the fate of dredge spoil placed along river corridors from a geomorphic and retrospective perspective. Such studies can provide guidance to rivers currently being dredged. The Apalachicola River in Florida was dredged from the 1950s for several decades, with disposal on the floodplain, sand bars and open water during the navigation project. One of the larger mounds, disposal site 40 (DS 40) or locally called “Sand Mountain,” originated in an artificial cutoff and stands ~22 m high and extends ~10 ha in area. Because this section of river was a problem for navigation when dredging was being conducted, detailed historical survey sheets with topographic and bathymetric data exist. We analyze the local floodplain and channel geospatially and compile related dredging and disposal data to examine the geomorphic changes of this feature and the adjoining river. Poor placement has resulted in this and other dredge spoil mounds returning sediment to the river through mass wasting and lateral erosion. Intermittent sediment pulses have altered channel morphology adjacent to the spoil mound with the channel becoming wider and shallower than originally and width-depth ratio increasing three-fold. Although dredging of this river has not been conducted for nearly two decades, we found that poor placement of spoil can continue to stress and alter a river with sediment input in the decades that follow. Based on our findings, dredging downstream of distributaries may result in poor outcomes. Locally, dredge spoil placement in cut-off channels close to the river, the outer bend of meanders, and upstream of problem or shallow areas should be avoided. Findings of this study have implications to other anthropogenic deposits including loose material left on floodplains in areas of intensive sand and gravel mining in streams and floodplains.
Presenters Joann Mossa
University Of Florida
Co-authors
YC
Yin-Hsuen Chen
University Of Florida
Development of a modeling system to study the impact of freshwater diversions on estuarine systemsView Abstract Watch Recording
Oral Presentation 03:00 PM - 03:15 PM (America/Chicago) 2020/12/01 21:00:00 UTC - 2020/12/31 21:15:00 UTC
Due to climate change, the strength and frequency of heavy rainfall and flooding events have been changing along with the associated use of protective measures such as diversions directing river water to coastal areas. Bonnet Carre Spillway (BCS) is the flood control structure on Mississippi River protecting the City of New Orleans from flooding by diverting about 250,000 cfs from the river into Lake Pontchartrain (LP). For the first time ever BCS was operated for three years in a row in 2018, 2019 and 2020. It was also operated twice in the same year for the first time in 2019. It is important to understand the transport of this excess freshwater through LP into the Mississippi Sound estuarine system, the physical processes driving this transport, the extent of freshwater impact and how rapidly conditions change. In this study, we develop a COAWST-based modeling system that covers a study area including the LP basin system, Mississippi Sound, Mobile Bay and the continental shelf of Mississippi Bight. The river forcing includes discharge of Mississippi River as well as other local rivers including those of the LP system. The atmospheric forcing is provided by NOAA’s High-Resolution Rapid Refresh model. With a multi-nested approach, the model resolves the channels (i.e. Pass Manchac, Rigolets and Chef Menteur Pass) in between Maurepas, Pontchartrain and Mississippi Sound allowing us to study circulation and exchange in and between different water bodies of the system. The freshwater flow into LP via BCS crevasse is added so that the modeling system may be setup to study diversion operation scenarios. This modeling approach will help us better understand the dynamics and physical drivers of freshwater transport in this region and the impact of incoming freshwater on HAB formations, onset of Hypoxia, oyster habitat, etc.
Presenters Kemal Cambazoglu
The University Of Southern Mississippi
Co-authors Brandy Armstrong
The University Of Southern Mississippi
SK
SANDEEP KALATHUPURATH KUTTAN
The University Of Southern Missisippi
DB
Diana Bernstein
University Of Southern Mississippi
JW
Jerry Wiggert
The University Of Southern Mississippi
Beneficial Use and Sustainability in Coastal Alabama View Abstract Watch Recording
Oral Presentation 03:00 PM - 03:30 PM (America/Chicago) 2020/12/01 21:00:00 UTC - 2020/12/31 21:30:00 UTC
Coastal wetlands provide numerous ecosystem services including improved water quality, valuable habitat for fish and wildlife, and shoreline protection. However, their resilience is largely a function of various environmental stressors which can reduce elevation and result in loss of coastal habitat. In systems where natural sedimentation processes are limited or have been altered, beneficial use (BU) of dredged sediment is a great opportunity to create, enhance, or restore ecosystems. Moffatt & Nichol developed two sustainability plans to provide a framework for BU at the Lightning Point Restoration Project in Bayou La Batre, AL, and more broadly in the Grand Bay and Portersville Bay region of Alabama. The Lightning Point Long-term Site Sustainability Plan addresses thin-layer placement of material to increase the marsh elevation and/or respond to localized impacts, and modification of the existing breakwaters to maintain their function. These measures are proposed as adaptive management activities to support the long-term performance and sustainability of the restored area. The Framework for Beneficial Use in the Grand Bay and Portersville Bay Region addresses BU of maintenance dredging material to nourish existing habitat through thin-layer placement, restore historic habitat locations, and/or create new habitat in strategic locations. This plan investigates sediment sources within the region, identifies project opportunities, and provides a framework for BU. Each sustainability plan contains a framework which is presented as steps with respective requirements and recommendations to support development, design, and implementation of the proposed measures. Steps one through six include: project planning and development, engineering and design, regulations and permitting, construction, management and logistics, and monitoring. Both sustainability plans are regarded as “living” documents to be updated and edited with novel data and advances in analysis, management approaches, policies, and partnerships. They serve as the present-day basis for activity and future project development.
Presenters Katherine Dawson
Moffatt & Nichol
Co-authors Meg Goecker
Moffatt & Nichol
GS
Gerald Songy
Moffatt & Nichol
NC
Nicholas Cox
Moffatt & Nichol
Mary Kate Brown
The Nature Conservancy
JH
Judy Haner
The Nature Conservancy
The University of Southern Mississippi
Moffatt & Nichol
University of Florida
USM Gulf Coast Geospatial Center
Mississippi State University
+ 1 more speakers. View All
No moderator for this session!
 Kasea Price
Gulf Coast Research Laboratory, USM
The University of Southern Missisippi
NOAA/NMFS/SEFSC
NMFS SERO Habitat Conservation Division
+86 more attendees. View All
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